On Sun, Jun 17, 2018 at 12:30 PM Brian Wolff <bawolff@gmail.com> wrote:

Woo!

Good to see us moving forward to newer codecs.

What is the expected impact on transcode time/memory usage? (As in, will large videos still transcode fine or would they potentially hit limits sooner?)

Using the same CPU thread count, typical files take about 3-4 times longer with the configuration we've got ready. This doesn't seem to be a major problem at low resolutions, but higher resolutions may need to have the limits raised for very long videos like conference talks. Memory usage may be higher but I've not specifically noticed a major difference between VP8 and VP9 there.

This could be improved significantly by updating to libvpx 1.7 and a matching version of ffmpeg that supports macroblock row multithreading: this means that we'll be able to use more than 4 threads for HD videos, which should allow using all cores on a 20-core/40-thread machine if it's not loaded up with other files.

The necessary libraries are released; we just need to backport the newer packages to Debian 9 I believe. Don't yet know whether this will be an easy or hard task.

Now that you mention it I am concerned about the time limit on very long videos, so I'll take another look at the packaging backport and see if we can knock that out quickly. :)

-- brion